1. Field of the Invention
This invention is in the area of snap buckles, specifically a snap buckle with a safety feature that prevents inadvertent or unwanted release.
2. Description of the Related Art
Snap buckles are known in the art, beginning with U.S. Pat. No. 4,150,464 to Tracy. Variations on this buckle type include U.S. Pat. Nos. 4,569,106 to Lovato; 4,672,725 to Kasai; 4,688,337 to Dillner and Smous; 4,987,661 to Kasai; 5,131,122 to Lovato; 5,291,641 to Morino; and 5,438,737 and 5,459,910, both to Anscher.
All these prior art devices have a male plug member with one or two side catch arms, and a female socket member. When the male plug is inserted into the female socket, the catch arms engage openings in each side of the female socket, locking the male plug and female socket together. Disengagement is effected by pushing in the portions of the catch arms that protrude through the openings in the female socket.
Very few variations on the snap buckle incorporate an additional safety feature to prevent inadvertent or unwanted disengagement of the buckle. The very nature of the snap buckle design makes it easy to disengage, and so an additional safety feature is important in situations where the buckle may be inadvertently disengaged, or where young children may try to disengage the buckle and put themselves at risk of injury. For example, snap buckles are often used to join child restraining straps in grocery carts and strollers. Inadvertent or deliberate disengagement by a young child is inconvenient at best, and at worst can be dangerous.
Two basic approaches have been taken in the prior art to incorporating an additional safety feature into a snap buckle:
The first approach, shown in U.S. Pat. Nos. 4,793,032 to Crowle, 4,825,515 to Wolterstorff, Jr., and 5,774,956 to French and Wigger, employs an additional catch to supplement either one or two side catch arms. The additional catch is incorporated into the male plug member and is accessible directly through an opening in the top of the female socket member. The catch arms and the additional catch are operated on simultaneously to disengage the male plug from the female socket.
A major disadvantage of the above devices, however, is that the additional catch cannot be easily disengaged, even when an adult may want to do so. For example, the additional catches of U.S. Pat. Nos. 4,793,032 and 5,774,956 must be fully depressed into the interior of the female socket to clear the socket and allow disengagement. The top socket opening cannot be made large enough to enable the catch to be easily disengaged by hand, since the catch's size (and thus the opening's size) is limited by the need to provide clearance to depress the side catch arms.
A further disadvantage is that in the engagement process, the additional catch must be depressed to enter the female socket, making engagement more difficult. The additional catch cannot protrude suitably out of the top socket opening (desirable for visibility and intuitiveness of operation), since the further it protrudes, the more difficult it is to engage and disengage the catch.
The additional catch shown in U.S. Pat. No. 4,825,515 is also cumbersome to disengage. It is not centrally located on the female socket, making it less visible and less intuitive to operate.
The second approach to incorporating a safety feature into a snap buckle entails blocking the action of the side catch arms, thus preventing disengagement of the buckle. U.S. Pat. Nos. 4,912,950 to Crowle and 5,144,725 to Krauss employ locking assemblies within the female socket, which rotate to block the action of the side catch arms. The sockets of these devices are complex, entail multiple parts, and are difficult to manufacture in one piece. Further, it is difficult to manually unlock the side catch arms--it is best done with a screwdriver or other key-type tool. This is more involved and less intuitive than, say, simply pushing a button to disengage an additional catch body.
Thus it can be seen that a snap buckle with a safety feature that is difficult for a young child to operate simultaneously with the side catch arms, yet easier and more intuitive for an adult to operate than prior art, would be a significant improvement.
Accordingly, several objects and advantages of my invention are:
It is difficult for a small child to comprehend and operate. The button on the top of the female socket must be pushed down at the same time as the side catch arms are pushed in. Moreover, it is easier and more intuitive for an adult to operate than prior art devices. The button which is depressed to disengage the additional catch can be made suitably large--since it is part of the female socket, and not part of the male plug, its size is not as limited by the need to allow clearance for the action of the side catch arms. This aids visibility and intuitiveness of adult operation.
In addition, engagement of the additional catch is automatic--the additional catch need not be depressed to enter the female socket, unlike the aforementioned prior art. Lastly, the female socket can be manufactured in one piece, thereby minimizing manufacturing steps and cost, unlike those prior art devices which use rotating locking assemblies.
Further objects and advantages of my invention will become apparent from a consideration of the drawings and ensuing description.